Active substance/active substance preparations in aqueous solutions are subject in part to instabilities, which can result in reduced efficacy or bioactivity and increased toxicity or intolerance reactions. This applies both to classical pharmaceuticals as well as to peptide active substances or active substances containing proteins. The stability of pharmaceutical active substances can be positively affected by modification of their structure (internal) or by the addition of suitable excipients (external).
A common method for external stabilization of pharmaceutical active substances is the utilization of suitable excipients. Excipients for stabilizing active substances can be generally grouped into the following categories: Sugar and polyols, amino acids, amines, salts, polymers and tensides.
Sugars and polyols are frequently used as nonspecific stabilizers. In the biological active substances, their stabilizing effect is attributed predominantly to “preferential exclusion” (Xie and Timasheff, 1997, Biophysical Chemistry, 64(1-3), 25-43; Xie and Timasheff, 1997, Protein Science, 6(1), 211-221; Timasheff, 1998, Advances in protein chemistry, 51, 355-432). When selecting sugars for use with biological active substances, reducing sugars are generally avoided. Saccharose and trehalose are used of choice as non-reducing sugars. Other examples of suitable excipients are glucose, sorbitol, glycerol (Boctor and Mehta, 1992, Journal of Pharmacy and Pharmacology, 44 (7), 600-3; Timasheff, 1993, Annual review of biophysics and biomolecular structure, 22, 67-97; Chang et al., 1993, Pharmaceutical Research, 10(10), 1478-83) and mannitol (Hermann et al., 1996, Pharmaceutical Biotechnology, 9 (Formulation, Characterization, and Stability of Protein Drugs), 303-328; Chan et al., 1996, Pharmaceutical Research, 13(5), 756-761). In addition, it is well known that a wide range of polymers have a stabilizing effect on pharmaceutical active substances, predominantly on proteins such as antibodies, for example. Human serum albumin (HAS), frequently used in the past, has very satisfactory stabilizing and aggregation inhibiting properties; however, because of its potential contamination with “blood borne” pathogens, is unsuitable. Of the polymers known to date, hydroxypropyl-β-cyclodextrin (HP-β-CD) has been shown to be particularly suitable, because it also can be safely administered parenterally. Other examples are the higher molecular weight dextrans (18 to 82 kD), PVP, heparin, type A and B gelatin and hydroxyethyl starches (HES), heparin, dextran sulfate, polyphosphoric acid, poly-L-glutamic acid, poly-L-lysine.
Along with sugars and polyols, amino acids can be used alone or in combination with other excipients for stabilizing. Amino acids are used preferably for stabilizing proteins. For example, the addition of histidine, glycine, sodium aspartate (Na-Asp), glutamate and lysine hydrochloride (Lys-HCl) inhibits the aggregation of rhKGF (recombinant human Keratinocyte Growth Factor) in 10 mM of sodium phosphate buffer (pH 7.0) together with 5% mannitol (Zhang et al., 1995, Biochemistry, 34 (27), 8631-41). The combination of amino acids and propylene glycol improves the structural stability of rhCNTF (recombinant human cilliary neurotrophic factor) (Dix et al., 1995, Pharmaceutical Research (Supplement), 12, p. 97). Lysine and arginine increase thermostability of IL-1R (Tm—increase), whereas glycine and alanine have a destabilizing effect (Remmele et al., 1998, Pharmaceutical Research, 15(2), 200-208).
Furthermore, the stability of pharmaceutical active substances is enhanced by different drying processes. Drying is carried out, however, generally also in the presence of excipients, which maintain the stability of the active substances and are intended to improve the properties of the dry powder. A critical factor in stabilization by drying is the immobilization of the active substance in an amorphous matrix. The amorphous state has a high viscosity with low molecular mobility and low reactivity. Thus, advantageous excipients must be capable of forming an amorphous matrix having as high a temperature of vitrification as possible, in which the active substance is imbedded. Accordingly, the choice of excipients depends especially on their stabilization capabilities. Furthermore, factors like the pharmaceutical acceptability of the excipient and its influence on particle formation, dispersibility and flow characteristics, however, play a critical role, especially if it is a spray drying process.
Spray drying represents a particularly suitable process for increasing the chemical and physical stability of peptide/protein analogous pharmaceutical active substances (Maa et al., 1998, Pharmaceutical Research, 15(5), 768-775). Spray drying is being used increasingly especially in the field of pulmonary therapy (U.S. Pat. No. 5,626,874; U.S. Pat. No. 5,972,388; Broadhead et al., 1994, J. Pharm. Pharmacol., 46(6), 458-467), because in the meanwhile administration by inhalation also represents an alternative in the treatment of systemic diseases (WO 99/07340). The pre-requisite is that the mean particle size of the powder is in the range of from 1-10 μm, preferably between 1-7.5 μm, so that the particles can reach the deeper lung sections and consequently reach the blood circulation. DE-A-179 22 07 describes, for example, the manufacture of corresponding spray dried particles. In the meanwhile, a number of processes for manufacturing corresponding powders are described (WO 95/31479; WO 96/09814; WO 96/32096; WO 96/32149; WO 97/41833; WO 97/44013; WO 98/16205; WO 98/31346; WO 99/66903; WO 00/10541; WO 01/13893; Maa et al., 1998, supra; Vidgrén et al., 1987, Int. J. Pharmaceutics, 35, 139144; Niven et al., 1994, Pharmaceutical Research, 11(8), 1101-1109).
Likewise, sugars and their alcohols are suitable as excipients (e.g. trehalose, lactose, saccharose or mannitol) as well as various polymers (Maa et al., 1997, Pharm. Development and Technology, 2(3), 213-223; Maa et al., 1998, supra; Dissertation Adler, 1998, University of Erlangen; Costantino, et al., 1998, J. Pharm. Sci., 87(11), 1406-1411). The predominantly used excipients, however, have different drawbacks. The addition of trehalose and mannitol, for example, adversely affects flow properties of spray dried formulations (C. Bosquillon et al., 2001 Journal of Controlled Release, 70(3), 329-339). Mannitol tends also to recrystallize at a concentration of more than 20% wt (Costantino et al., 1998, supra), whereby stabilizing effects diminish dramatically. Although lactose, a frequently used excipient, improves flow properties of spray dried formulations (C. Bosquillon et al., 2001, supra), it is, however, problematic in the formulation of peptide active substances/active substances containing proteins, because lactose can involve destabilizing Maillard reactions with peptides/proteins because of its reducing characteristic.
In spray drying of antibodies without the addition of stabilizers there is a development of the secondary structure and consequently loss of bioactivity in virtue of regular dehydration, heat and shearing. When this is done, the previously introverted hydrophobic parts of the antibody become extraverted. This occurs to a greater extent at the hydrophobic interfaces between the water droplets arising in the course of spray drying and the air. In addition, antibodies aggregate within the aqueous phase to dimers or higher order aggregates. These aggregations are frequently irreversible. In addition, the high temperature at which the proteins are sprayed represents a critical parameter. In virtue of the high energy application can result in a destabilization of the peptide bonds and in denaturisation of the antibody. Furthermore, there is aggregate formation of spray-dried antibodies during the storage period of the powder. In particular, the residual water content in the powder has negative effects in this case. Protein aggregates are characterized by reduced or absent biological activity and enhanced antigenicity.
Lactosucrose as well multiple sugars (oligosaccharides) designated as coupling sugars with the main components maltosylsucrose and glucosylsucrose are used in the foodstuffs sector. They are used as bulking agents and dispersing agents along with sweeteners like aspartam, as mildly sweet components in chewing gum, for stabilizing against crystallization of trehalose syrups or as so-called NDOs (non-digestible oligosaccharides). An improvement and stabilization of the sweetening quality of asparagyl peptides or of the sweet-sour ratio in drinks containing ballast and sweetener agents is also well-known (US 2003/0059511, EP 1 223 175, DE 199 53 727). U.S. Pat. No. 5,489,577 and EP 0 630 651 further disclose the use of oligosaccharides for stabilizing suspensions comprised of therapeutic proteins and fatty or oil bases. It is stated that the proteins, without pre-mixing with the oligosaccharides would lose their activity at the time of mixing and working with the hydrophobic, semi-solid masses. The stabilization potential over the period of storage in hydrophobic mixtures or in powders is not mentioned at all.
An object of the invention is to provide novel excipients for use in manufacturing pharmaceutical preparations. The corresponding preparations should be characterized inter alia by good long-term stability.
A further object of the present invention is to provide novel excipients for use in manufacturing dried pharmaceutical preparations. The corresponding pharmaceutical preparation in powder form should be characterized by good long-term stability and, if possible, by inhalability.
A further object of the present invention is to provide novel excipients for use in manufacturing peptide pharmaceutical formulations or pharmaceutical formulations containing proteins, in particular for those produced by spray drying. The corresponding peptide pharmaceutical preparation/pharmaceutical preparation containing proteins should be characterized by good long-term stability and, if possible, by inhalability.
A further object of the present invention is to provide novel excipients for use in formulating therapeutic antibodies or antibody derivatives, in particular for those produced by spray drying. The corresponding antibody-containing pharmaceutical preparation should be characterized by good long-term stability and, if possible, by inhalability.
A further object of the present invention is to provide corresponding pharmaceutical preparations for administration by inhalation, whether in the form of a dry powder, a dosing aerosol containing a propellant gas or an inhalation solution not containing a propellant gas.
The objects upon which the invention is based are achieved by means of the following embodiments and by the subject matter/processes represented in the patent claims.